[65.03] Mining the Galaxy: White Dwarfs in the SDSS

S. J. Kleinman (Apache Pt. Observatory)

White dwarf stars (WDs) are among the oldest stars in the
Galaxy and they offer unique clues to its structure and
evolution. The Sloan Digital Sky Survey (SDSS) has proven
very good at identifying white dwarf stars. While quite good
lists of candidate white dwarfs can be identified by their
SDSS photometric colors, I concentrate here on
spectroscopically identified WDs from the SDSS spectroscopic
survey. We have solidly identified roughly 1500 DA WDs, 100
DBs, 160 DCs, 50 DQs, 60 DZs, 20 DH WDs. Since the SDSS is
predominantly a galaxy survey and we only ``haphazardly''
target certain WDs for spectroscopy, the relative numbers of
observed WD subtypes (and their temperatures, etc.) are not
necessarily representative of the Galaxy at large.
Nonetheless, this new sample of identified WDs is a
significant addition to the known WDs (2300 DAs, 200 DBs,
300 DCs, 90 DQs, and 70 DZs in the online McCook and Sion
catalog) and will aid greatly in our understanding of some
of the more rare types of WDs. In addition, there are indeed
some prospects for being able to identify a completeness
estimate for our observed stars so we may eventually arrive
at a vastly improved white dwarf luminosity function.

Here, I describe our white dwarf sample and point out a
small subset of interesting objects already identified. I
will also briefly discuss the future of WD research in the
SDSS and the prospects for an improved luminosity function.